Integrated circuits (ICs) include circuitry and multiple logic blocks that may be configured to perform any of a variety of functions. Signals from one logic block may be routed to another logic block through routing wires or routing paths on the IC.
Generally, different logic blocks may be placed anywhere on the IC. Some logic blocks may be placed nearer to each other while other logic blocks may be placed further apart from each other. Depending on the distance between the logic blocks, routing wires that connect one logic block to another may have different lengths.
The lengths of the wires may range from a few microns to hundreds or even thousands of microns. The speed of the signals propagating through the wires may be affected by the different lengths of the wires. Generally, a signal travelling through a longer routing path will experience more delay than a signal travelling through a shorter routing path.
Apart from the length of the wires, the width of the routing wires may also affect the speed of the signals and consequently, the overall speed of the IC. Typically, as process nodes become smaller, more circuits may be placed on the IC. As such, thinner routing wires may be needed in order to accommodate all the different circuits on the IC.
However, thinner wires may further affect the overall speed of the IC as the electrical resistance of a wire is directly proportional to the length of the wire and inversely proportional to the area (i.e., the width or diameter) of the wire. In other words, electrical signals travelling through longer and thinner wires may be slower compared to electrical signals travelling through shorter and wider wires.
Additionally, as there may generally be different paths connecting different circuitry and logic blocks on an IC, pass gates are generally used to route signals through various paths on the IC. For instance, a routing path or wire may branch out to two different paths and a signal travelling through that routing path may be routed to either one of the branches. As such, the overall speed of the IC may also be limited by the strength of these pass gates.
Therefore, based on all these different factors, there may be some undesirable delay as signals are routed through various routing paths on the IC. The delay associated with the routing paths may adversely affect the overall performance of the IC.